America Ferrera Says No One Told Her the ‘Barbie’ Sleepover Had a ‘Sexy’ Dress Code — and She Wore ‘Grandma’ PJs

The cast revealed they had a slumber party together and though Margot Robbie and others wore "silky nightgowns," Ferrera says she did not

America Ferrera didn’t get the memo about her sleepover’s dress code.

On Monday, Kelly Clarkson invited the Barbie cast on her eponymous talk show. Margot Robbie, who plays one of the Barbies in the upcoming film, dished about a sleepover that was organized by writer-director Greta Gerwig.

“We had a Barbie sleepover. It was as fun as it sounds,” Robbie, 32, told host Clarkson, 41.

“We all went to Claridge’s, which is a really gorgeous hotel in London,” she continued. “We all, like, shared beds, and, like, wore our pajamas, and ordered room service, and played games, and found out that, like, America is exceptionally competitive.”

Ferrera, 39, then replied saying she didn’t receive the dress code memo for the overnight shindig. “I am extremely competitive and nobody told me that it was a sexy Barbie sleepover,” she said.

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“So everybody was in, like, really pretty silky nightgowns, and I was in, like, the most grandma floral twin set you could imagine,” the Ugly Betty star said.

Robbie explained that Ferrera’s ensemble was absolutely adorable.

“She somehow simultaneously looked like an old day but a 5-year-old at the same time. It was the cutest. I mean, she was the cutest little thing. You’d put, like, a toddler in to go to bed and then she was, like, rousing at us for not knowing the rules.”

Clarkson agreed with Ferrera’s aggressive gaming nature, adding, “If you’re not gonna compete, why are you here?”

Related: The 'Barbie' Movie Barbie Dolls Just Dropped — and All Eyes Are on Ryan Gosling's Ken

In October, the Sisterhood of the Traveling Pants actress opened up to PEOPLE about starring as Gloria in the highly anticipated film about the iconic Mattel doll.

"People don't have any idea what to expect [with the film], and I think that that's the right vibe," she said. "Whatever you think it is, it's not that. It's something else."

She added that ​​Barbie "is just awesome in the truest sense, and I'm so excited for people to share in that awesomeness."

She noted that her time on set was a dream come true and every detail was breathtaking.

"All of the craftsmanship is just awe-inspiring, and the sets themselves were magnificent and awesome, as was the wardrobe and the hair and the makeup," she explained.

Related: America Ferrera Teases Upcoming 'Barbie' Film: Fans 'Don't Have Any Idea What to Expect'

The mother of two, who shares two children with husband Ryan Piers, revealed that her kids have no idea she'll be starring in the upcoming Barbie movie.

"They don't really have any context for it," Ferrera told PEOPLE. "So one day [they might care]. But not now, they're still too young."

Barbie opens in theaters on July 21. 

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